It was a great pleasure a few weeks ago to be the guest of Robert Buhagiar, the organ builder on Malta and Gozo. I'd imagine that few can have curatorship of more historic instruments than he and the two islands are a gem in the organ world.

We went to see another instrument at Qrendi and this was extraordinary, the sound becoming more grand and more profound as more of the upper Ripieno was added. I imagine that the Ripieno harmonics produce beat frequencies as sub-harmonics, creating a very grand sound.

It's quite well documented in the video. The buildup of sound with the harmonics was surprising and extraordinary. Not piercing and certainly added gravitas. Rather the effect of the French Plein Jeu, but more focussed.

The point about the Ripieno is that it's a buildup of octaves and fifths. So 8ft and 4ft Principal, then Nazard, Fifteenth, Larigot, 1ft, fifth above that and the octave above that. Of course they break back to the lower octaves at the upper end of the keyboards.

But perhaps people are familiar with the mock 32ft effect by playing fifths on the pedalboard. A fifth produces a beat note an octave below the lower note of the fifth. So as one starts to add octaves and fifths their beats add notes below them, and if these beats are strong enough, they will add octaves lower still. It's for this reason that the Ripieno adds gravitas whilst apparently going higher.

The point about the Ripieno is that it's a buildup of octaves and fifths. So 8ft and 4ft Principal, then Nazard, Fifteenth, Larigot, 1ft, fifth above that and the octave above that. Of course they break back to the lower octaves at the upper end of the keyboards.

But perhaps people are familiar with the mock 32ft effect by playing fifths on the pedalboard. A fifth produces a beat note an octave below the lower note of the fifth. So as one starts to add octaves and fifths their beats add notes below them, and if these beats are strong enough, they will add octaves lower still. It's for this reason that the Ripieno adds gravitas whilst apparently going higher.

Best wishes

David P

But wouldn't you expect the same with quint mixtures and cymbels? Or is it more to do with the sound quality of Italian principal pipes?

I don't know. It's definitely a result of no tierces in the mixtures and might be psychological as the Ripieno is progressively built up. It was the 1778 instrument at Qrendi which particularly demonstrated the effect. Unfortunately my camera ran out of memory for video.

The place is an extraordinarily progressive culture of preservation which becomes even more valuable when passionately restored and maintained.